Polymeric roofing membranes have been employed to cover flat or low-sloped roofs. Both thermoset and thermoplastic membranes have been employed. One type of thermoplastic membrane includes olefin-based thermoplastic resins. It is believed that one commercial source of an olefin-based resin employed in these membranes includes blends of thermoplastic resins that are prepared in situ or in sequence. In other words, the blends are believed to be formed during synthesis of the thermoplastic resins.